Publications by authors named "Julien Cappelle"

52 Publications

Effect of an ear cleaner instillation containing lipacids in a model of re-acidification of the external auditory canal in dogs.

Vet Dermatol 2022 Jul 6. Epub 2022 Jul 6.

Univ Lyon, VetAgro Sup, UP ICE, France.

Background: In humans, the acidic pH of the ear canal plays a protective role against infection and a change towards alkalinity of the external auditory canal (EAC) is a local factor in the progression of acute to chronic otitis externa (OE). The use of acidic preparations alone for treatment of OE without concurrent antibiotic use is well-documented in humans. In dogs, only one study has investigated the EAC pH in healthy dogs and in dogs with OE, and investigations to understand the role of EAC pH in the pathogenesis of canine OE are lacking.

Hypothesis/objectives: To obtain physiological EAC pH values in beagle dogs. To develop a model of re-acidification of the EAC in dogs and to investigate how an acidic solution may accelerate the return to a physiological pH.

Animals: Ten healthy beagle dogs in a laboratory setting.

Materials And Methods: A model of re-acidification of the EAC was developed by instillation of a pH 10.1 phosphate-buffered saline (PBS) solution and the subsequent acidic effect of an ear cleaner containing lipacids was evaluated in this model.

Results: Mean physiological EAC pH was 6.12 (± 0.36). EAC re-acidification took up to 9 h in this model. Mean pH values dropped immediately to 6.38 (± 0.27) on ears treated with an acidic ear cleaner. No abrupt drop was observed of the mean pH values for the control ears.

Conclusion And Clinical Importance: This study confirms that physiological EAC pH in dogs is acidic. This model of re-acidification of the EAC pH allows investigations on acidic properties of topical ear products in healthy ears.
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http://dx.doi.org/10.1111/vde.13101DOI Listing
July 2022

Childhood encephalitis in the Greater Mekong region (the SouthEast Asia Encephalitis Project): a multicentre prospective study.

Lancet Glob Health 2022 07;10(7):e989-e1002

National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

Background: Encephalitis is a worldwide public health issue, with a substantially high burden among children in southeast Asia. We aimed to determine the causes of encephalitis in children admitted to hospitals across the Greater Mekong region by implementing a comprehensive state-of-the-art diagnostic procedure harmonised across all centres, and identifying clinical characteristics related to patients' conditions.

Methods: In this multicentre, observational, prospective study of childhood encephalitis, four referral hospitals in Cambodia, Vietnam, Laos, and Myanmar recruited children (aged 28 days to 16 years) who presented with altered mental status lasting more than 24 h and two of the following minor criteria: fever (within the 72 h before or after presentation), one or more generalised or partial seizures (excluding febrile seizures), a new-onset focal neurological deficit, cerebrospinal fluid (CSF) white blood cell count of 5 per mL or higher, or brain imaging (CT or MRI) suggestive of lesions of encephalitis. Comprehensive diagnostic procedures were harmonised across all centres, with first-line testing was done on samples taken at inclusion and results delivered within 24 h of inclusion for main treatable causes of disease and second-line testing was done thereafter for mostly non-treatable causes. An independent expert medical panel reviewed the charts and attribution of causes of all the included children. Using multivariate analyses, we assessed risk factors associated with unfavourable outcomes (ie, severe neurological sequelae and death) at discharge using data from baseline and day 2 after inclusion. This study is registered with ClinicalTrials.gov, NCT04089436, and is now complete.

Findings: Between July 28, 2014, and Dec 31, 2017, 664 children with encephalitis were enrolled. Median age was 4·3 years (1·8-8·8), 295 (44%) children were female, and 369 (56%) were male. A confirmed or probable cause of encephalitis was identified in 425 (64%) patients: 216 (33%) of 664 cases were due to Japanese encephalitis virus, 27 (4%) were due to dengue virus, 26 (4%) were due to influenza virus, 24 (4%) were due to herpes simplex virus 1, 18 (3%) were due to Mycobacterium tuberculosis, 17 (3%) were due to Streptococcus pneumoniae, 17 (3%) were due to enterovirus A71, 74 (9%) were due to other pathogens, and six (1%) were due to autoimmune encephalitis. Diagnosis was made within 24 h of admission to hospital for 83 (13%) of 664 children. 119 (18%) children had treatable conditions and 276 (42%) had conditions that could have been preventable by vaccination. At time of discharge, 153 (23%) of 664 children had severe neurological sequelae and 83 (13%) had died. In multivariate analyses, risk factors for unfavourable outcome were diagnosis of M tuberculosis infection upon admission (odds ratio 3·23 [95% CI 1·04-10·03]), coma on day 2 (2·90 [1·78-4·72]), supplementary oxygen requirement (1·89 [1·25-2·86]), and more than 1 week duration between symptom onset and admission to hospital (3·03 [1·68-5·48]). At 1 year after inclusion, of 432 children who were discharged alive from hospital with follow-up data, 24 (5%) had died, 129 (30%) had neurological sequelae, and 279 (65%) had completely recovered.

Interpretation: In southeast Asia, most causes of childhood encephalitis are either preventable or treatable, with Japanese encephalitis virus being the most common cause. We provide crucial information that could guide public health policy to improve diagnostic, vaccination, and early therapeutic guidelines on childhood encephalitis in the Greater Mekong region.

Funding: Institut Pasteur, Institut Pasteur International Network, Fondation Merieux, Aviesan Sud, INSERM, Wellcome Trust, Institut de Recherche pour le Développement (IRD), and Fondation Total.
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http://dx.doi.org/10.1016/S2214-109X(22)00174-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9210261PMC
July 2022

Quantification and characterisation of commensal wild birds and their interactions with domestic ducks on a free-range farm in southwest France.

Sci Rep 2022 Jun 13;12(1):9764. Epub 2022 Jun 13.

IHAP, ENVT, INRAE, Université de Toulouse, Toulouse, France.

The role of commensal birds in the epidemiology of pathogens in poultry farms remains unclear. Our study aimed to identify potential key species for interactions with domestic ducks on one free-range duck farm in southwest France. Methods combined direct individual observations on duck outdoor foraging areas, network analysis, and general linear mixed models of abundances. Results showed a wide diversity of wild bird species visiting foraging areas, heavily dominated in frequency by White wagtails (Motacilla alba) and Sparrows (Passer domesticus and Passer montanus). These also were the only species seen entering duck premises or perching on drinkers in the presence of ducks. Moreover, White wagtails were the species most frequently observed on the ground and in close proximity to ducks. Network analysis suggested the role of White wagtails and Sparrows in linking ducks to other wild birds on the farm. The abundance of White wagtails was positively associated with open vegetation, with the presence of ducks and particularly in the afternoon, while the abundance of Sparrows was positively associated only with the fall-winter season. By precisely characterising interactions, the study was able to identify few wild bird species which should be prioritized in infectious investigations at the interface with poultry.
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http://dx.doi.org/10.1038/s41598-022-13846-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9192735PMC
June 2022

Longitudinal Survey of Coronavirus Circulation and Diversity in Insectivorous Bat Colonies in Zimbabwe.

Viruses 2022 04 9;14(4). Epub 2022 Apr 9.

Faculty of Veterinary Science, University of Zimbabwe, Harare P.O. Box MP 167, Zimbabwe.

Background: Studies have linked bats to outbreaks of viral diseases in human populations such as SARS-CoV-1 and MERS-CoV and the ongoing SARS-CoV-2 pandemic.

Methods: We carried out a longitudinal survey from August 2020 to July 2021 at two sites in Zimbabwe with bat-human interactions: Magweto cave and Chirundu farm. A total of 1732 and 1866 individual bat fecal samples were collected, respectively. Coronaviruses and bat species were amplified using PCR systems.

Results: Analysis of the coronavirus sequences revealed a high genetic diversity, and we identified different sub-viral groups in the and genus. The established sub-viral groups fell within the described sub-genera: , , , and and for sub-genera: , and . Our results showed an overall proportion for CoV positive PCR tests of 23.7% at Chirundu site and 16.5% and 38.9% at Magweto site for insectivorous bats and , respectively.

Conclusions: The higher risk of bat coronavirus exposure for humans was found in December to March in relation to higher viral shedding peaks of coronaviruses in the parturition, lactation and weaning months of the bat populations at both sites. We also highlight the need to further document viral infectious risk in human/domestic animal populations surrounding bat habitats in Zimbabwe.
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http://dx.doi.org/10.3390/v14040781DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9031365PMC
April 2022

Circulating serogroups of Leptospira in swine from a 7-year study in France (2011-2017).

Porcine Health Manag 2022 Apr 4;8(1):15. Epub 2022 Apr 4.

VetAgro Sup, Université de Lyon, USC 1233, Marcy L'Etoile, France.

Background: Leptospirosis is a widespread zoonotic disease caused by pathogenic Leptospira and is responsible for significant economic porcine livestock losses. Knowledge of Leptospira serogroups and their distributions is important for evaluation of the relevance of leptospirosis management measures, including use of the prophylactic vaccine that was recently made available in France. A retrospective study was conducted to determine the relationships between different circulating Leptospira serogroups. Pigs from across France presenting clinical signs suggestive of leptospirosis were tested with the microagglutination test (MAT) between 2011 and 2017. We used weighted averages to determine serogroup distributions according to MAT results and considering cross-reactions.

Results: A total of 19,395 pig sera, mostly from Brittany, were tested, and 22.7% were found to be positive for at least one Leptospira serogroup. Analysis of the 4,346 seropositive results for which the putative infective serogroup could be defined, revealed that two out of ten serogroups were much more frequent than the others: Australis (48.5%) and Icterohaemorrhagiae (38.2%). Other serogroups, including Autumnalis, Panama, Ballum, Tarassovi, Sejroe, Grippotyphosa, Bataviae, and Pomona, were less common.

Conclusions: Although diagnostic laboratory data cannot be extrapolated to infer the distribution of Leptospira serogroups at the nationwide scale in France, the analysis of such data can provide an overview of the relationship between circulating Leptospira serogroups in space and time. During the last decade, protection against the serogroups Australis and Icterohaemorrhagiae would have prevented most of the clinical porcine leptospirosis cases in the large number of farms that we studied. In the future, epidemiological information related to circulating Leptospira serogroups should be extracted from data with a standardized approach for use in nationwide or international surveillance and prophylactic strategy support.
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http://dx.doi.org/10.1186/s40813-022-00257-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8978166PMC
April 2022

Dynamics of Antibodies to Ebolaviruses in an Bat Colony in Cameroon.

Viruses 2022 03 9;14(3). Epub 2022 Mar 9.

Transvihmi, Institut de Recherche pour le Développement (IRD), University of Montpellier, Inserm, 34394 Montpellier, France.

The ecology of ebolaviruses is still poorly understood and the role of bats in outbreaks needs to be further clarified. Straw-colored fruit bats () are the most common fruit bats in Africa and antibodies to ebolaviruses have been documented in this species. Between December 2018 and November 2019, samples were collected at approximately monthly intervals in roosting and feeding sites from 820 bats from an colony. Dried blood spots (DBS) were tested for antibodies to Zaire, Sudan, and Bundibugyo ebolaviruses. The proportion of samples reactive with GP antigens increased significantly with age from 0-9/220 (0-4.1%) in juveniles to 26-158/225 (11.6-70.2%) in immature adults and 10-225/372 (2.7-60.5%) in adult bats. Antibody responses were lower in lactating females. Viral RNA was not detected in 456 swab samples collected from 152 juvenile and 214 immature adult bats. Overall, our study shows that antibody levels increase in young bats suggesting that seroconversion to Ebola or related viruses occurs in older juvenile and immature adult bats. Multiple year monitoring would be needed to confirm this trend. Knowledge of the periods of the year with the highest risk of Ebolavirus circulation can guide the implementation of strategies to mitigate spill-over events.
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http://dx.doi.org/10.3390/v14030560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8951055PMC
March 2022

Spatial-temporal patterns and risk factors for human leptospirosis in Thailand, 2012-2018.

Sci Rep 2022 03 24;12(1):5066. Epub 2022 Mar 24.

Université de Lyon, INRAE, VetAgro Sup, UMR EPIA, 69280, Marcy l'Etoile, France.

Leptospirosis is a globally important zoonotic disease. The disease is particularly important in tropical and subtropical countries. Infections in humans can be caused by exposure to infected animals or contaminated soil or water, which are suitable for Leptospira. To explore the cluster area, the Global Moran's I index was calculated for incidences per 100,000 population at the province level during 2012-2018, using the monthly and annual data. The high-risk and low-risk provinces were identified using the local indicators of spatial association (LISA). The risk factors for leptospirosis were evaluated using a generalized linear mixed model (GLMM) with zero-inflation. We also added spatial and temporal correlation terms to take into account the spatial and temporal structures. The Global Moran's I index showed significant positive values. It did not demonstrate a random distribution throughout the period of study. The high-risk provinces were almost all in the lower north-east and south parts of Thailand. For yearly reported cases, the significant risk factors from the final best-fitted model were population density, elevation, and primary rice crop arable areas. Interestingly, our study showed that leptospirosis cases were associated with large areas of rice production but were less prevalent in areas of high rice productivity. For monthly reported cases, the model using temperature range was found to be a better fit than using percentage of flooded area. The significant risk factors from the model using temperature range were temporal correlation, average soil moisture, normalized difference vegetation index, and temperature range. Temperature range, which has strongly negative correlation to percentage of flooded area was a significant risk factor for monthly data. Flood exposure controls should be used to reduce the risk of leptospirosis infection. These results could be used to develop a leptospirosis warning system to support public health organizations in Thailand.
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http://dx.doi.org/10.1038/s41598-022-09079-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8948194PMC
March 2022

Detection and genetic diversity of Mopeia virus in Mastomys natalensis from different habitats in the Limpopo National Park, Mozambique.

Infect Genet Evol 2022 03 5;98:105204. Epub 2022 Jan 5.

MIVEGEC, University of Montpellier, IRD, CNRS, 34394 Montpellier, France; Faculty of Veterinary Science, University of Zimbabwe, P.O. Box MP167, Harare, Zimbabwe. Electronic address:

Mammarenaviruses have been a growing concern for public health in Africa since the 1970s when Lassa virus cases in humans were first described in west Africa. In southern Africa, a single outbreak of Lujo virus was reported to date in South Africa in 2008 with a case fatality rate of 80%. The natural reservoir of Lassa virus is Mastomys natalensis while for the Lujo virus the natural host has yet to be identified. Mopeia virus was described for the first time in M. natalensis in the central Mozambique in 1977 but few studies have been conducted in the region. In this study, rodents were trapped between March and November 2019in villages, croplands fields and mopane woodland forest. The aim was to assess the potential circulation and to evaluate the genetic diversity of mammarenaviruses in M. natalensis trapped in the Limpopo National Park and its buffer zone in Massingir district, Mozambique. A total of 534 M. natalensis were screened by RT-PCR and the overall proportion of positive individuals was 16.9%. No significant differences were detected between the sampled habitats (χ = 0.018; DF = 1; p = 0.893). The Mopeia virus (bootstrap value 91%) was the Mammarenavirus circulating in the study area sites, forming a specific sub-clade with eight different sub-clusters. We concluded that Mopeia virus circulates in all habitats investigated and it forms a different sub-clade to the one reported in central Mozambique in 1977.
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http://dx.doi.org/10.1016/j.meegid.2022.105204DOI Listing
March 2022

Genetic identification of bat species for pathogen surveillance across France.

PLoS One 2022 4;17(1):e0261344. Epub 2022 Jan 4.

ANSES-Nancy Laboratory for Rabies and Wildlife, WHO Collaborating Centre for Research and Management in Zoonoses Control, OIE Reference Laboratory for Rabies, European Union Reference Laboratory for Rabies, European Union Reference Laboratory for Rabies Serology, Malzéville, France.

With more than 1400 chiropteran species identified to date, bats comprise one-fifth of all mammalian species worldwide. Many studies have associated viral zoonoses with 45 different species of bats in the EU, which cluster within 5 families of bats. For example, the Serotine bats are infected by European Bat 1 Lyssavirus throughout Europe while Myotis bats are shown infected by coronavirus, herpesvirus and paramyxovirus. Correct host species identification is important to increase our knowledge of the ecology and evolutionary pattern of bat viruses in the EU. Bat species identification is commonly determined using morphological keys. Morphological determination of bat species from bat carcasses can be limited in some cases, due to the state of decomposition or nearly indistinguishable morphological features in juvenile bats and can lead to misidentifications. The overall objective of our study was to identify insectivorous bat species using molecular biology tools with the amplification of the partial cytochrome b gene of mitochondrial DNA. Two types of samples were tested in this study, bat wing punches and bat faeces. A total of 163 bat wing punches representing 22 species, and 31 faecal pellets representing 7 species were included in the study. From the 163 bat wing punches tested, a total of 159 were genetically identified from amplification of the partial cyt b gene. All 31 faecal pellets were genetically identified based on the cyt b gene. A comparison between morphological and genetic determination showed 21 misidentifications from the 163 wing punches, representing ~12.5% of misidentifications of morphological determination compared with the genetic method, across 11 species. In addition, genetic determination allowed the identification of 24 out of 25 morphologically non-determined bat samples. Our findings demonstrate the importance of a genetic approach as an efficient and reliable method to identify bat species precisely.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0261344PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8726466PMC
January 2022

Longitudinal monitoring in Cambodia suggests higher circulation of alpha and betacoronaviruses in juvenile and immature bats of three species.

Sci Rep 2021 12 17;11(1):24145. Epub 2021 Dec 17.

Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh, Cambodia.

Recent studies suggest that coronaviruses circulate widely in Southeast Asian bat species and that the progenitors of the SARS-Cov-2 virus could have originated in rhinolophid bats in the region. Our objective was to assess the diversity and circulation patterns of coronavirus in several bat species in Southeast Asia. We undertook monthly live-capture sessions and sampling in Cambodia over 17 months to cover all phases of the annual reproduction cycle of bats and test specifically the association between their age and CoV infection status. We additionally examined current information on the reproductive phenology of Rhinolophus and other bat species presently known to occur in mainland southeast China, Vietnam, Laos and Cambodia. Results from our longitudinal monitoring (573 bats belonging to 8 species) showed an overall proportion of positive PCR tests for CoV of 4.2% (24/573) in cave-dwelling bats from Kampot and 4.75% (22/463) in flying-foxes from Kandal. Phylogenetic analysis showed that the PCR amplicon sequences of CoVs (n = 46) obtained clustered in Alphacoronavirus and Betacoronavirus. Interestingly, Hipposideros larvatus sensu lato harbored viruses from both genera. Our results suggest an association between positive detections of coronaviruses and juvenile and immature bats in Cambodia (OR = 3.24 [1.46-7.76], p = 0.005). Since the limited data presently available from literature review indicates that reproduction is largely synchronized among rhinolophid and hipposiderid bats in our study region, particularly in its more seasonal portions (above 16° N), this may lead to seasonal patterns in CoV circulation. Overall, our study suggests that surveillance of CoV in insectivorous bat species in Southeast Asia, including SARS-CoV-related coronaviruses in rhinolophid bats, could be targeted from June to October for species exhibiting high proportions of juveniles and immatures during these months. It also highlights the need to develop long-term longitudinal surveys of bats and improve our understanding of their ecology in the region, for both biodiversity conservation and public health reasons.
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http://dx.doi.org/10.1038/s41598-021-03169-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8683416PMC
December 2021

Mapping of Ebola virus spillover: Suitability and seasonal variability at the landscape scale.

PLoS Negl Trop Dis 2021 08 23;15(8):e0009683. Epub 2021 Aug 23.

CIRAD, UMR ASTRE, Montpellier, France.

The unexpected Ebola virus outbreak in West Africa in 2014 involving the Zaire ebolavirus made clear that other regions outside Central Africa, its previously documented niche, were at risk of future epidemics. The complex transmission cycle and a lack of epidemiological data make mapping areas at risk of the disease challenging. We used a Geographic Information System-based multicriteria evaluation (GIS-MCE), a knowledge-based approach, to identify areas suitable for Ebola virus spillover to humans in regions of Guinea, Congo and Gabon where Ebola viruses already emerged. We identified environmental, climatic and anthropogenic risk factors and potential hosts from a literature review. Geographical data layers, representing risk factors, were combined to produce suitability maps of Ebola virus spillover at the landscape scale. Our maps show high spatial and temporal variability in the suitability for Ebola virus spillover at a fine regional scale. Reported spillover events fell in areas of intermediate to high suitability in our maps, and a sensitivity analysis showed that the maps produced were robust. There are still important gaps in our knowledge about what factors are associated with the risk of Ebola virus spillover. As more information becomes available, maps produced using the GIS-MCE approach can be easily updated to improve surveillance and the prevention of future outbreaks.
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http://dx.doi.org/10.1371/journal.pntd.0009683DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8425568PMC
August 2021

Agro-Environmental Determinants of Leptospirosis: A Retrospective Spatiotemporal Analysis (2004-2014) in Mahasarakham Province (Thailand).

Trop Med Infect Dis 2021 Jun 28;6(3). Epub 2021 Jun 28.

CIRAD, UMR ASTRE, 34398 Montpellier, France.

Leptospirosis has been recognized as a major public health concern in Thailand following dramatic outbreaks. We analyzed human leptospirosis incidence between 2004 and 2014 in Mahasarakham province, Northeastern Thailand, in order to identify the agronomical and environmental factors likely to explain incidence at the level of 133 sub-districts and 1982 villages of the province. We performed general additive modeling (GAM) in order to take the spatial-temporal epidemiological dynamics into account. The results of GAM analyses showed that the average slope, population size, pig density, cow density and flood cover were significantly associated with leptospirosis occurrence in a district. Our results stress the importance of livestock favoring leptospirosis transmission to humans and suggest that prevention and control of leptospirosis need strong intersectoral collaboration between the public health, the livestock department and local communities. More specifically, such collaboration should integrate leptospirosis surveillance in both public and animal health for a better control of diseases in livestock while promoting public health prevention as encouraged by the One Health approach.
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http://dx.doi.org/10.3390/tropicalmed6030115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8293432PMC
June 2021

Formula for the estimation of urine osmolality in healthy cats.

Res Vet Sci 2021 Mar 9;135:121-126. Epub 2021 Jan 9.

Department of Companion Animal, Internal Medicine Unit - UMR 754 INRA "Infections virales et pathologie comparée" (Cadoré), VetAgro Sup - Campus Vétérinaire, Marcy l'Etoile, France.

A simple and intuitive formula for the estimation of urine osmolality (U) using the measured concentrations of major active urine osmolytes over a wide range of urine dilutions was proposed in healthy cats. Sixty-three urine samples were retrieved using ultrasound-guided cystocentesis from sixteen healthy cats under 5 years of age receiving intravenous infusion over a period of 24 h. Samples were collected at baseline (T), T, T, T, and T. Urine osmolality was measured using a freezing-point osmometer, and the concentrations of osmolytes (urea, sodium, glucose, and potassium) were evaluated. A simple linear regression model for a clinical use was selected, and the agreement between the calculated and actual urine osmolalities was assessed. Urinary concentrations of urea, sodium and glucose were the three variables included in the model with the lowest AIC. Urine osmolality can be predicted accurately and precisely using urine urea, sodium and glucose with the following equation: U = 1.25 × urea (mmol/l) or 20.87 × urea (g/l) + 1.1 × sodium (mmol/l) + 67 × glucose (mmol/l) or 3.72 × glucose (mg/dl). The concordance correlation coefficient for repeated measures between the actual and the calculated urine osmolality was extremely close to 1, which supported a high agreement: 0.996 (CI 95%: [0.993; 0.998]). In a population of healthy cats, urine osmolality can be predicted accurately and precisely using urinary urea, sodium and glucose concentrations. Similar formulae could potentially be established to help the clinician in pathological situations.
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http://dx.doi.org/10.1016/j.rvsc.2021.01.009DOI Listing
March 2021

Patterns of foraging activity and fidelity in a southeast Asian flying fox.

Mov Ecol 2020 Nov 10;8(1):46. Epub 2020 Nov 10.

UMR ASTRE, CIRAD, INRAE, Université de Montpellier, Montpellier, France.

Background: Improved understanding of the foraging ecology of bats in the face of ongoing habitat loss and modification worldwide is essential to their conservation and maintaining the substantial ecosystem services they provide. It is also fundamental to assessing potential transmission risks of zoonotic pathogens in human-wildlife interfaces. We evaluated the influence of environmental and behavioral variables on the foraging patterns of Pteropus lylei (a reservoir of Nipah virus) in a heterogeneous landscape in Cambodia.

Methods: We employed an approach based on animal-movement modeling, which comprised a path-segmentation method (hidden Markov model) to identify individual foraging-behavior sequences in GPS data generated by eight P. lylei. We characterized foraging localities, foraging activity, and probability of returning to a given foraging locality over consecutive nights. Generalized linear mixed models were also applied to assess the influence of several variables including proxies for energetic costs and quality of foraging areas.

Results: Bats performed few foraging bouts (area-restricted searches) during a given night, mainly in residential areas, and the duration of these decreased during the night. The probability of a bat revisiting a given foraging area within 48 h varied according to the duration previously spent there, its distance to the roost site, and the corresponding habitat type. We interpret these fine-scale patterns in relation to global habitat quality (including food-resource quality and predictability), habitat-familiarity and experience of each individual.

Conclusions: Our study provides evidence that heterogeneous human-made environments may promote complex patterns of foraging-behavior and short-term re-visitation in fruit bat species that occur in such landscapes. This highlights the need for similarly detailed studies to understand the processes that maintain biodiversity in these environments and assess the potential for pathogen transmission in human-wildlife interfaces.
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http://dx.doi.org/10.1186/s40462-020-00232-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7652672PMC
November 2020

Nipah virus circulation at human-bat interfaces, Cambodia.

Bull World Health Organ 2020 Aug 19;98(8):539-547. Epub 2020 Jun 19.

Institut Pasteur du Cambodge, Phnom Penh, Cambodia.

Objective: To better understand the potential risks of Nipah virus emergence in Cambodia by studying different components of the interface between humans and bats.

Methods: From 2012 to 2016, we conducted a study at two sites in Kandal and Battambang provinces where fruit bats () roost. We combined research on: bat ecology (reproductive phenology, population dynamics and diet); human practices and perceptions (ethnographic research and a knowledge, attitude and practice study); and Nipah virus circulation in bat and human populations (virus monitoring in bat urine and anti-Nipah-virus antibody detection in human serum).

Findings: Our results confirmed circulation of Nipah virus in fruit bats (28 of 3930 urine samples positive by polymerase chain reaction testing). We identified clear potential routes for virus transmission to humans through local practices, including fruit consumed by bats and harvested by humans when Nipah virus is circulating, and palm juice production. Nevertheless, in the serological survey of 418 potentially exposed people, none of them were seropositive to Nipah virus. Differences in agricultural practices among the regions where Nipah virus has emerged may explain the situation in Cambodia and point to actions to limit the risks of virus transmission to humans.

Conclusion: Human practices are key to understanding transmission risks associated with emerging infectious diseases. Social science disciplines such as anthropology need to be integrated in health programmes targeting emerging infectious diseases. As bats are hosts of major zoonotic pathogens, such integrated studies would likely also help to reduce the risk of emergence of other bat-borne diseases.
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http://dx.doi.org/10.2471/BLT.20.254227DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411325PMC
August 2020

A moisturizer formulated with glycerol and propylene glycol accelerates the recovery of skin barrier function after experimental disruption in dogs.

Vet Dermatol 2020 Oct 6;31(5):344-e89. Epub 2020 Jul 6.

VetAgro Sup, UP ICE, Université de Lyon, 69280, Marcy l'Étoile, France.

Background: Moisturizers are foundational therapies for human atopic dermatitis. In veterinary medicine, the use of moisturizers has been recommended by an expert committee to alleviate skin dryness that would occur, for example, in canine atopic dermatitis (cAD). However, little is known regarding the effects of moisturizers on the skin barrier.

Hypothesis/objectives: To investigate the effects of a moisturizer on skin barrier recovery in a canine model of chronic mechanical barrier disruption.

Animals: Six healthy beagle dogs maintained in a laboratory setting.

Methods And Materials: A model of chronic skin barrier disruption was simulated by tape stripping on both sides of the thorax. The moisturizer then was applied twice daily for one week to one side of the thorax, while the other hemithorax was left untreated. The effects were evaluated by measurement of transepidermal water loss (TEWL) at various times during skin barrier recovery, and by histological assessment of the disrupted skin one week after moisturizer application.

Results: Overall, TEWL was reduced, epidermal thickness was lower, stratum corneum thickness was greater and the intensity of the dermal inflammatory infiltrate was reduced for treated sites.

Conclusions And Clinical Importance: These results suggest a potential benefit of the moisturizer for improving skin barrier function, which is frequently altered in chronic inflammatory dermatoses such as cAD.
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http://dx.doi.org/10.1111/vde.12859DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7586792PMC
October 2020

Spatial epidemiology of Japanese encephalitis virus and other infections of the central nervous system infections in Lao PDR (2003-2011): A retrospective analysis.

PLoS Negl Trop Dis 2020 05 26;14(5):e0008333. Epub 2020 May 26.

Department of Population Health and Disease Prevention, University of California, Irvine, United States of America.

Background: Central nervous system (CNS) infections are important contributors to morbidity and mortality and the causative agents for ~50% patients are never identified. The causative agents of some CNS infections have distinct spatial and temporal patterns.

Methodology/principal Findings: Here we present the results of a spatial epidemiological and ecological analysis of CNS infections in Lao PDR (2003-2011). The data came from hospitalizations for suspected CNS infection at Mahosot Hospital in Vientiane. Out of 1,065 patients, 450 were assigned a confirmed diagnosis. While many communities in Lao PDR are in rural and remote locations, most patients in these data came from villages along major roads. Japanese encephalitis virus ((JEV); n = 94) and Cryptococcus spp. (n = 70) were the most common infections. JEV infections peaked in the rainy season and JEV patients came from villages with higher surface flooding during the same month as admission. JEV infections were spatially dispersed throughout rural areas and were most common in children. Cryptococcus spp. infections clustered near Vientiane (an urban area) and among adults.

Conclusions/significance: The spatial and temporal patterns identified in this analysis are related to complex environmental, social, and geographic factors. For example, JEV infected patients came from locations with environmental conditions (surface water) that are suitable to support larger mosquito vector populations. Most patients in these data came from villages that are near major roads; likely the result of geographic and financial access to healthcare and also indicating that CNS diseases are underestimated in the region (especially from more remote areas). As Lao PDR is undergoing major developmental and environmental changes, the space-time distributions of the causative agents of CNS infection will also likely change. There is a major need for increased diagnostic abilities; increased access to healthcare, especially for rural populations; and for increased surveillance throughout the nation.
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http://dx.doi.org/10.1371/journal.pntd.0008333DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7274481PMC
May 2020

Serological Evidence for Japanese Encephalitis and West Nile Virus Infections in Domestic Birds in Cambodia.

Front Vet Sci 2020 29;7:15. Epub 2020 Jan 29.

Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh, Cambodia.

Mosquito-borne flaviviruses with an enzootic transmission cycle like Japanese encephalitis virus (JEV) and West Nile virus (WNV) are a major public health concern. The circulation of JEV in Southeast Asia is well-documented, and the important role of pigs as amplification hosts for the virus is long known. The influence of other domestic animals especially poultry that lives in high abundance and close proximity to humans is not intensively analyzed. Another understudied field in Asia is the presence of the closely related WNV. Such analyses are difficult to perform due to the intense antigenic cross-reactivity between these viruses and the lack of suitable standardized serological assays. The main objective of this study was to assess the prevalence of JEV and WNV flaviviruses in domestic birds, detailed in chickens and ducks, in three different Cambodian provinces. We determined the flavivirus seroprevalence using an hemagglutination inhibition assay (HIA). Additionally, we investigated in positive samples the presence of JEV and WNV neutralizing antibodies (nAb) using foci reduction neutralization test (FRNT). We found 29% (180/620) of the investigated birds positive for flavivirus antibodies with an age-depended increase of the seroprevalence (OR = 1.04) and a higher prevalence in ducks compared to chicken (OR = 3.01). Within the flavivirus-positive birds, we found 43% (28/65) with nAb against JEV. We also observed the expected cross-reactivity between JEV and WNV, by identifying 18.5% double-positive birds that had higher titers of nAb than single-positive birds. Additionally, seven domestic birds (10.7%) showed only nAb against WNV and no nAb against JEV. Our study provides evidence for an intense JEV circulation in domestic birds in Cambodia, and the first serological evidence for WNV presence in Southeast Asia since decades. These findings mark the need for a re-definition of areas at risk for JEV and WNV transmission, and the need for further and intensified surveillance of mosquito-transmitted diseases in domestic animals.
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http://dx.doi.org/10.3389/fvets.2020.00015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7000427PMC
January 2020

Whole genome sequencing and phylogenetic characterization of a novel bat-associated picornavirus-like virus with an unusual genome organization.

Infect Genet Evol 2020 03 27;78:104130. Epub 2019 Nov 27.

Institut Pasteur, Biology of Infection Unit, Pathogen Discovery Laboratory, Inserm U1117, Paris, France; National Veterinary School of Alfort, Paris-Est University, Maisons-Alfort, 94704, Cedex, France. Electronic address:

The order Picornavirales is one of the most important viral orders in terms of virus diversity and genome organizations, ranging from a mono- or bi-cistronic expression strategies to the recently described poly-cistronic Polycipiviridae viruses. We report here the description and characterization of a novel picorna-like virus identified in rectal swabs of frugivorous bats in Cambodia that presents an unusual genome organization. Kandabadicivirus presents a unique genome architecture and distant phylogenetic relationship to the proposed Badiciviridae family. These findings highlight a high mosaicism of genome organizations among the Picornavirales.
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http://dx.doi.org/10.1016/j.meegid.2019.104130DOI Listing
March 2020

Insights into the Host Range, Genetic Diversity, and Geographical Distribution of Jingmenviruses.

mSphere 2019 11 6;4(6). Epub 2019 Nov 6.

Institut Pasteur, Biology of Infection Unit, Inserm U1117, Pathogen Discovery Laboratory, Institut Pasteur, Paris, France

Jingmenvirus is a recently identified group of segmented RNA viruses phylogenetically linked with unsegmented viruses. Primarily identified in various tick genera originating in China, Jingmenvirus geographical distribution has rapidly expanded to cover Africa, South America, Caribbean, and Europe. The identification of Jingmen-related viruses in various mammals, including febrile humans, opens the possibility that Jingmenviruses may be novel tick-borne arboviruses. In this study, we aimed at increasing knowledge of the host range, genetic diversity, and geographical distribution of Jingmenviruses by reporting for the first time the identification of Jingmenviruses associated with ticks originating in the French Antilles (Guadeloupe and Martinique islands), with ticks in Lao PDR, and with ticks in metropolitan France, and from urine of bats in Cambodia. Analyses of the relationships between the different Jingmenvirus genomes resulted in the identification of three main phylogenic subclades, each of them containing both tick-borne and mammal-borne strains, reinforcing the idea that Jingmenviruses may be considered as tick-borne arboviruses. Finally, we estimated the prevalence of Jingmenvirus-like infection using luciferase immunoprecipitation assay screening (LIPS) of asymptomatic humans and cattle highly exposed to tick bites. Among 70 French human, 153 Laotian human, and 200 Caribbean cattle sera tested, only one French human serum was found (slightly) positive, suggesting that the prevalence of Jingmenvirus human and cattle infections in these areas is probably low. Several arboviruses emerging as new pathogens for humans and domestic animals have recently raised public health concern and increased interest in the study of their host range and in detection of spillover events. Recently, a new group of segmented -related viruses, the Jingmenviruses, has been identified worldwide in many invertebrate and vertebrate hosts, pointing out the issue of whether they belong to the arbovirus group. The study presented here combined whole-genome sequencing of three tick-borne Jingmenviruses and one bat-borne Jingmenvirus with comprehensive phylogenetic analyses and high-throughput serological screening of human and cattle populations exposed to these viruses to contribute to the knowledge of Jingmenvirus host range, geographical distribution, and mammalian exposure.
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http://dx.doi.org/10.1128/mSphere.00645-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835211PMC
November 2019

[Tropical forests, changes in land uses and emerging infectious hazards].

Sante Publique 2019 May;S1(HS):91-106

Tropical forests have the greatest biodiversity in macroorganisms on the planet, and they are also the richest in myriads of microorganisms for which so little is known today. Over the last 50 years, many of these microbial forms, that are naturally embedded into wildlife or the environment, e.g. soil, water, have revealed to be more or less dangerous pathogens for people exposed to these new natural threats, i.e. emerging infectious diseases. Here, we discuss about the extraordinary diversity of microorganisms that are present in tropical rainforests. We first present the main global distribution patterns for microbial forms at the interface between tropical wildlife and human, and second we provide an epidemiological picture on how microbial transmission from wild animals or the environment to people operates in tropical areas through four case-studies. We examine the animal hosts or environment, and transmission mechanisms involved in spillover of zoonotic or environmentally-persistent microbes, and identify land-use changes through deforestation for the development of agriculture, and contacts with wildlife notably through bush meat hunting as major drivers that facilitate mixing of diverse animal hosts and their microbial communities with human during practices. With an increase of deforestation in the tropics and more contacts between wildlife and people, new emerging disease events with high epidemic and pandemic potential will happen, that should guide new health policies and strategies at the global scale.
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http://dx.doi.org/10.3917/spub.190.0091DOI Listing
May 2019

primarily forages in residential areas in Kandal, Cambodia.

Ecol Evol 2019 Apr 13;9(7):4181-4191. Epub 2019 Mar 13.

Institut Pasteur du Cambodge Phnom Penh Cambodia.

Bats are the second most species-rich Mammalian order and provide a wide range of ecologically important and economically significant ecosystem services. Nipah virus is a zoonotic emerging infectious disease for which pteropodid bats have been identified as a natural reservoir. In Cambodia, Nipah virus circulation has been reported in , but little is known about the spatial distribution of the species and the associated implications for conservation and public health.We deployed Global Positioning System (GPS) collars on 14 to study their movements and foraging behavior in Cambodia in 2016. All of the flying foxes were captured from the same roost, and GPS locations were collected for 1 month. The habitats used by each bat were characterized through ground-truthing, and a spatial distribution model was developed of foraging sites.A total of 13,643 valid locations were collected during the study. Our study bats flew approximately 20 km from the roost each night to forage. The maximum distance traveled per night ranged from 6.88-105 km and averaged 28.3 km. Six of the 14 bats visited another roost for at least one night during the study, including one roost located 105 km away.Most foraging locations were in residential areas (53.7%) followed by plantations (26.6%). Our spatial distribution model confirmed that residential areas were the preferred foraging habitat for , although our results should be interpreted with caution due to the limited number of individuals studied. : Our findings suggest that the use of residential and agricultural habitats by may create opportunities for bats to interact with humans and livestock. They also suggest the importance of anthropogenic habitats for conservation of this vulnerable and ecologically important group in Cambodia. Our mapping of the probability of occurrence of foraging sites will help identification of areas where public awareness should be promoted regarding the ecosystem services provided by flying foxes and potential for disease transmission through indirect contact.
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http://dx.doi.org/10.1002/ece3.5046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6468066PMC
April 2019

A Novel Virus Identified in Stools.

Microbiol Resour Announc 2019 Apr 11;8(15). Epub 2019 Apr 11.

Institut Pasteur, Biology of Infection Unit, Inserm U1117, Pathogen Discovery Laboratory, Paris, France

is a recently recognized viral family within the order with unusual genome organization and phylogenetic placement. Viruses belonging to this family were only reported from arthropod hosts. We describe here the first full genome of a distant polycipivirus-related virus identified in frugivorous bat stools in Cambodia.
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http://dx.doi.org/10.1128/MRA.01662-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6460041PMC
April 2019

Frequency of bacteriuria in dogs with chronic kidney disease: A retrospective study of 201 cases.

J Vet Intern Med 2019 Mar 14;33(2):640-647. Epub 2019 Feb 14.

Unité de Médecine Interne, Ecole Nationale Vétérinaire d'Alfort, Maisons Alfort, France.

Background: Studies have shown an increased prevalence of positive urine culture (PUC) in cats with chronic kidney disease (CKD); no information is available in dogs.

Objectives: To document the PUC frequency in a cohort of dogs with CKD, determine risk factors for PUC, and identify associations between clinicopathologic data and PUC.

Animals: Two hundred one client-owned dogs with CKD.

Methods: Retrospective, observational study. Dogs recruited from 2 veterinary teaching hospitals were included if they were diagnosed with CKD and had a culture performed on urine collected by cystocentesis. The PUC frequency was calculated, multivariate analysis was performed to identify risk factors, and associations with clinicopathologic data were investigated.

Results: Sixty-five dogs (32%) with CKD had PUC, including 8 (28%) in International Renal Interest Society (IRIS) stage 1; only 8% showed signs of a urinary tract infection. Escherichia coli was the most common isolate (67%). A PUC was more likely in females (odds ratio [OR], 3.22; 95% confidence interval [CI], 1.67-6.37; P < .001) than males and in dogs with isosthenuria (OR, 2.48; 95% CI, 1.24-5.03; P = .01) than in dogs with urine-specific gravity 1.013-1.024. A positive leukocyte esterase test and microorganisms found by urine sediment analysis were significantly associated with PUC (both P < .001).

Conclusions And Clinical Importance: Dogs with CKD, even IRIS stage 1, have a high frequency of PUC and most cases are asymptomatic. A urine culture could be considered in the routine evaluation of dogs with CKD, but the clinical relevance of a PUC remains unknown and needs further evaluation.
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http://dx.doi.org/10.1111/jvim.15434DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6430954PMC
March 2019

Extreme temperature event and mass mortality of insectivorous bats.

Eur J Wildl Res 2019 29;65(3):41. Epub 2019 Apr 29.

4Institut Pasteur du Cambodge, Phnom Penh, Cambodia.

A mass mortality event involving and bats occurred during a heat wave in April 2016 in Cambodia. This was investigated to clarify the causes of the die-off and assess the risk to public health. Field evidences, clinical signs, and gross pathology findings were consistent with a heat stress hypothesis. However, the detection of a novel bat paramyxovirus raises questions about its role as a contributing factor or a coincidental finding. Systematic documentation of bat die-offs related to extreme weather events is necessary to improve understanding of the effect of changing weather patterns on bat populations and the ecosystem services they provide.
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http://dx.doi.org/10.1007/s10344-019-1280-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7088037PMC
April 2019

Differential replication efficiencies between Japanese encephalitis virus genotype I and III in avian cultured cells and young domestic ducklings.

PLoS Negl Trop Dis 2018 12 18;12(12):e0007046. Epub 2018 Dec 18.

Department of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China.

Japanese encephalitis virus (JEV) genotype dominance has shifted to genotype I (GI) from genotype III (GIII) in China as demonstrated by molecular epidemiological surveillance. In this study, we performed a serological survey in JEV-non-vaccinated pigs to confirm JEV genotype shift at the sero-epidemiological level. The average ratio of GI/GIII infection was 1.87, suggesting co-circulation of GI and GIII infections with GI infection being more prevalent in pigs in China. To gain an insight into the reasons for this JEV genotype shift, the replication kinetics of seven recently-isolated JEV isolates including three GI strains and four GIII strains were compared in mosquito C6/36 cells, chicken fibroblast cells (DF-1) and porcine iliac artery endothelial cells (PIEC). We observed that GI strains replicated more efficiently than GIII strains in DF-1 and PIEC cells, particularly in DF-1 cells with titers reaching 22.9-225.3 fold higher than GIII strains. This shows an enhanced replication efficiency of GI viruses in avian cells. To examine this enhanced replication efficiency in vivo, young domestic ducklings were used as the animal model and inoculated with GI and GIII strains at day 2 post-hatching. We observed that GI-inoculated ducklings developed higher viremia titers and displayed a comparatively longer viremic duration than GIII-inoculated ducklings. These results conform to the hypothesis of an enhanced replication efficiency for GI viruses in birds. There are 36 amino acid differences between GI and GIII viruses, some of which may be responsible for the enhanced replication efficiency of GI viruses in birds. Based on these findings, we speculated that the enhanced replication of GI viruses in birds would have resulted in higher exposure and therefore infection in mosquitoes, which could result in an increased transmission efficiency of GI viruses in the birds-mosquitoes-birds enzootic transmission cycle, thereby contributing to JEV genotype shift.
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http://dx.doi.org/10.1371/journal.pntd.0007046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6314627PMC
December 2018

A remotely sensed flooding indicator associated with cattle and buffalo leptospirosis cases in Thailand 2011-2013.

BMC Infect Dis 2018 Nov 29;18(1):602. Epub 2018 Nov 29.

Université Clermont Auvergne, Université de Lyon, INRA, VetAgro Sup, UMR EPIA, 63122, Saint Genès Champanelle, France.

Background: Leptospirosis is an important zoonotic disease worldwide, caused by spirochetes bacteria of the genus Leptospira. In Thailand, cattle and buffalo used in agriculture are in close contact with human beings. During flooding, bacteria can quickly spread throughout an environment, increasing the risk of leptospirosis infection. The aim of this study was to investigate the association of several environmental factors with cattle and buffalo leptospirosis cases in Thailand, with a focus on flooding.

Method: A total of 3571 urine samples were collected from cattle and buffalo in 107 districts by field veterinarians from January 2011 to February 2013. All samples were examined for the presence of leptospirosis infection by loop-mediated isothermal amplification (LAMP). Environmental data, including rainfall, percentage of flooded area (estimated by remote sensing), average elevation, and human and livestock population density were used to build a generalized linear mixed model.

Results: A total of 311 out of 3571 (8.43%) urine samples tested positive by the LAMP technique. Positive samples were recorded in 51 out of 107 districts (47.66%). Results showed a significant association between the percentage of the area flooded at district level and leptospirosis infection in cattle and buffalo (p = 0.023). Using this data, a map with a predicted risk of leptospirosis can be developed to help forecast leptospirosis cases in the field.

Conclusions: Our model allows the identification of areas and periods when the risk of leptospirosis infection is higher in cattle and buffalo, mainly due to a seasonal flooding. The increased risk of leptospirosis infection can also be higher in humans too. These areas and periods should be targeted for leptospirosis surveillance and control in both humans and animals.
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http://dx.doi.org/10.1186/s12879-018-3537-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6267035PMC
November 2018

Ebola Virus Maintenance: If Not (Only) Bats, What Else?

Viruses 2018 10 9;10(10). Epub 2018 Oct 9.

ASTRE, Uni. Montpellier, CIRAD, INRA, 34398 Montpellier, France.

The maintenance mechanisms of ebolaviruses in African forest ecosystems are still unknown, but indirect evidences point at the involvement of some bat species. Despite intense research, the main bat-maintenance hypothesis has not been confirmed yet. The alternative hypotheses of a non-bat maintenance host or a maintenance community including, or not, several bat and other species, deserves more investigation. However, African forest ecosystems host a large biodiversity and abound in potential maintenance hosts. How does one puzzle out? Since recent studies have revealed that several bat species have been exposed to ebolaviruses, the common denominator to these hypotheses is that within the epidemiological cycle, some bats species must be exposed to the viruses and infected by these potential alternative hosts. Under this constraint, and given the peculiar ecology of bats (roosting behaviour, habitat utilisation, and flight mode), we review the hosts and transmission pathways that can lead to bat exposure and infection to ebolaviruses. In contrast to the capacity of bats to transmit ebolaviruses and other pathogens to many hosts, our results indicate that only a limited number of hosts and pathways can lead to the transmission of ebolaviruses to bats, and that the alternative maintenance host, if it exists, must be amongst them. A list of these pathways is provided, along with protocols to prioritise and investigate these alternative hypotheses. In conclusion, taking into account the ecology of bats and their known involvement in ebolaviruses ecology drastically reduces the list of potential alternative maintenance hosts for ebolaviruses. Understanding the natural history of ebolaviruses is a health priority, and investigating these alternative hypotheses could complete the current effort focused on the role of bats.
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http://dx.doi.org/10.3390/v10100549DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213544PMC
October 2018

Comparison of the dynamics of Japanese encephalitis virus circulation in sentinel pigs between a rural and a peri-urban setting in Cambodia.

PLoS Negl Trop Dis 2018 08 23;12(8):e0006644. Epub 2018 Aug 23.

Institut Pasteur du Cambodge, Epidemiology and Public Health Unit, Phnom Penh, Cambodia.

Japanese encephalitis is mainly considered a rural disease, but there is growing evidence of a peri-urban and urban transmission in several countries, including Cambodia. We, therefore, compared the epidemiologic dynamic of Japanese encephalitis between a rural and a peri-urban setting in Cambodia. We monitored two cohorts of 15 pigs and determined the force of infection-rate at which seronegative pigs become positive-in two study farms located in a peri-urban and rural area, respectively. We also studied the mosquito abundance and diversity in proximity of the pigs, as well as the host densities in both areas. All the pigs seroconverted before the age of 6 months. The force of infection was 0.061 per day (95% confidence interval = 0.034-0.098) in the peri-urban cohort and 0.069 per day (95% confidence interval = 0.047-0.099) in the rural cohort. Several differences in the epidemiologic dynamic of Japanese encephalitis between both study sites were highlighted. The later virus amplification in the rural cohort may be linked to the later waning of maternal antibodies, but also to the higher pig density in direct proximity of the studied pigs, which could have led to a dilution of mosquito bites at the farm level. The force of infection was almost identical in both the peri-urban and the rural farms studied, which shifts the classic epidemiologic cycle of the virus. This study is a first step in improving our understanding of Japanese encephalitis virus ecology in different environments with distinct landscapes, human and animal densities.
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http://dx.doi.org/10.1371/journal.pntd.0006644DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107123PMC
August 2018

How much does direct transmission between pigs contribute to Japanese Encephalitis virus circulation? A modelling approach in Cambodia.

PLoS One 2018 16;13(8):e0201209. Epub 2018 Aug 16.

CIRAD, UMR ASTRE, Phnom Penh, Cambodia.

Japanese Encephalitis (JE) is the most important cause of human encephalitis throughout Asia and the Pacific. Although JE is a vector-borne disease, it has been demonstrated experimentally that transmission between pigs can occur through direct contact. Whether pig-to-pig transmission plays a role in the natural epidemiological cycle of JE remains unknown. To assess whether direct transmission between pigs may occur under field conditions, we built two mathematical models of JE transmission incorporating vector-borne transmission alone or a combination of vector-borne and direct transmission. We used Markov Chain Monte Carlo (MCMC) techniques to estimate the parameters of the models. We fitted the models to (i) two serological datasets collected longitudinally from two pig cohorts (C1 and C2) during two periods of four months on a farm on the outskirts of Phnom-Penh, Cambodia and to (ii) a cross-sectional (CS) serological survey dataset collected from 505 swine coming from eight different provinces of Cambodia. In both cases, the model incorporating both vector-borne and direct transmission better explained the data. We computed the value of the basic reproduction number R0 (2.93 for C1, 2.66 for C2 and 2.27 for CS), as well as the vector-borne reproduction number Rpv and the direct transmission reproduction number Rpp. We then determined the contribution of direct transmission on R0 (11.90% for C1, 11.62% for C2 and 7.51% for CS). According to our results, the existence of pig-to-pig transmission is consistent with our swine serological data. Thus, direct transmission may contribute to the epidemiological cycle of JE in Cambodia. These results need to be confirmed in other eco-climatic settings, in particular in temperate areas where pig-to-pig transmission may facilitate the persistence of JE virus (JEV) during cold seasons when there are no or few mosquitoes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201209PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6095498PMC
February 2019
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